Multi-system air-conditioning machine in which outdoor unit is connected to a plurality of indoor units

Abstract

Electric expansion valves are provided midway along liquid-side pipes connected to indoor units. Electric flow control valves are provided midway along gas-side pipes connected to the indoor units. The indoor units detect air-conditioning loads, and a capability of a compressor is controlled in accordance with the sum of the air-conditioning loads. At the same time, the opening degrees of the flow control valves are controlled in accordance with the individual air-conditioning loads of the indoor units. In the heating operation mode, a high-pressure-side pressure of a refrigeration cycle is detected. When the high-pressure-side pressure becomes a preset value or more, an expansion valve and a flow control valve corresponding to an indoor unit whose operation is stopped are opened to predetermined opening degrees.

What is claimed is: 
     
       1. A multi-system air-conditioning machine in which a single outdoor unit is connected to a plurality of indoor units, comprising: a variable-capability compressor, provided in said outdoor unit, for drawing by vacuum a refrigerant through a suction port, compressing the refrigerant, and discharging the refrigerant through a discharge port;   a four-way valve for switching a flow direction of the refrigerant;   an outdoor heat exchanger, provided in said outdoor unit, for exchanging heat of the refrigerant flowing therethrough for heat of outer air;   a plurality of indoor heat exchangers, provided in said indoor units, respectively, for exchanging heat of the refrigerant flowing therethrough for heat of room air;   a plurality of electric expansion valves for decreasing a pressure of the refrigerant flowing therethrough;   a plurality of electric flow control valves for controlling an amount of refrigerant flowing therethrough;   a heat pump type refrigeration cycle in which said discharge port of said compressor is connected to said outdoor heat exchanger through said four-way valve, said outdoor heat exchanger is connected to said indoor heat exchangers through said expansion valves, and said indoor heat exchangers are connected to said suction port of said compressor through said flow control valves and said four-way valve;   means for flowing the refrigerant discharged from said compressor to said indoor heat exchangers through said four-way valve and said flow control valves, flowing the refrigerant output from said indoor heat exchangers to said outdoor heat exchanger through said expansion valves, and returning the refrigerant output from said outdoor heat exchanger to said compressor through said four-way valve, thereby executing a heating operation mode;   means, provided in said indoor units, for detecting air-conditioning loads based on a temperature of the room air;   means for controlling a capability of said compressor in accordance with a sum of the detected air-conditioning loads;   means for controlling opening degrees of said flow control valves in accordance with the detected air-conditioning loads;   means for detecting, in the heating operation mode, a pressure of the refrigerant flowing through a high-pressure-side of said refrigeration cycle; and   means for opening one of said expansion valves and one of said flow control valves corresponding to one of said indoor units whose operation is stopped to a predetermined opening degree when the detected pressure is not less than a preset value.   
     
     
       2. A multi-system air-conditioning machine according to claim 1, wherein said expansion valves and said flow control valves are pulse motor valves whose opening degrees are changed depending on the numbers of drive pulses supplied thereto. 
     
     
       3. A multi-system air-conditioning machine according to claim 1, further comprising means for flowing the refrigerant discharged from said compressor to said outdoor heat exchanger through said four-way valve, flowing the refrigerant output from said outdoor heat exchanger to said indoor heat exchangers through said expansion valves, and returning the refrigerant output from said indoor heat exchangers to said compressor through said flow control valves and said four-way valve, thereby executing a cooling operation mode. 
     
     
       4. A multi-system air-conditioning machine according to claim 1, further comprising: an inverter, provided in said outdoor unit, for outputting a voltage of a predetermined frequency; and   a compressor motor which is provided in said outdoor unit, which operates upon reception of the output from said inverter, and a rotating frequency of which changes in accordance with an output frequency of said inverter.   
     
     
       5. A multi-system air-conditioning machine according to claim 4, wherein said compressor is driven by said compressor motor. 
     
     
       6. A multi-system air-conditioning machine in which a single outdoor unit is connected to a plurality of indoor units, comprising: a variable-capability compressor, provided in said outdoor unit, for drawing by suction a refrigerant through a suction port, compressing the refrigerant, and discharging the refrigerant through a discharge port;   a four-way valve for switching a flow direction of the refrigerant;   an outdoor heat exchanger, provided in said outdoor unit, for exchanging heat of the refrigerant flowing therethrough for heat of outer air;   a plurality of indoor heat exchangers, provided in said indoor units, respectively, for exchanging heat of the refrigerant flowing therethrough for heat of room air;   a plurality of electric expansion valves for decreasing a pressure of the refrigerant flowing therethrough;   a plurality of electric flow control valves for controlling an amount of refrigerant flowing therethrough;   a heat pump type refrigeration cycle in which said discharge port of said compressor is connected to said outdoor heat exchanger through said four-way valve, said outdoor heat exchanger is connected to said indoor heat exchangers through said expansion valves, and said indoor heat exchangers are connected to said suction port of said compressor through said flow control valves and said four-way valve;   means for flowing the refrigerant discharged from said compressor to said indoor heat exchangers through said four-way valve and said flow control valves, flowing the refrigerant output from said indoor heat exchangers to said outdoor heat exchanger through said expansion valves, and returning the refrigerant output from said outdoor heat exchanger to said compressor through said four-way valve, thereby executing a heating operation mode;   means, provided in said indoor units, for detecting air-conditioning loads based on a temperature of the room air;   means for controlling a capability of said compressor in accordance with a sum of the detected air-conditioning loads;   means for controlling opening degrees of said flow control valves in accordance with the detected air-conditioning loads;   means for detecting, in the heating operation mode, a super-heat degree of the refrigerant in said outdoor heat exchanger;   means for controlling the opening degrees of said expansion valves so that the detected super-heat degree becomes a predetermined value;   means for opening, in the heating operation mode, one of said expansion valves and one of said flow control valves that correspond to one of said indoor units whose operation is stopped to small opening degrees;   means for detecting, in the heating operation mode, a temperature of the refrigerant flowing in the high-pressure-side of said refrigeration cycle; and   means for increasing an opening degree of one of said expansion vales corresponding to one of said indoor units whose operation is stopped when the detected temperature is not less than a preset value and when one of said expansion valves corresponding to operating one of said indoor units becomes almost completely opened.   
     
     
       7. A multi-system air-conditioning machine according to claim 6, wherein said expansion valves and said flow control valves are pulse motor valves whose opening degrees are changed depending on the numbers of drive pulses supplied thereto. 
     
     
       8. A multi-system air-conditioning machine according to claim 6, further comprising means for flowing the refrigerant discharged from said compressor to said outdoor heat exchanger through said four-way valve, flowing the refrigerant output from said outdoor heat exchanger to said indoor heat exchangers through said expansion valves, and returning the refrigerant output from said indoor heat exchangers to said compressor through said flow control valves and said four-way valve, thereby executing a cooling operation mode. 
     
     
       9. A multi-system air-conditioning machine according to claim 6, further comprising: an inverter, provided in said outdoor unit, for outputting a voltage of a predetermined frequency; and   a compressor motor which is provided in said outdoor unit, which operates upon reception of the output from said inverter, and a rotating frequency of which changes in accordance with an output frequency of said inverter.   
     
     
       10. A multi-system air-conditioning machine according to claim 9, wherein said compressor is driven by said compressor motor.